U.S. patent number 6,022,292 [Application Number 09/250,780] was granted by the patent office on 2000-02-08 for method of adjusting an engine load signal used by a transmission controller.
This patent grant is currently assigned to Deere & Company. Invention is credited to Trent Lynn Goodnight.
United States Patent |
6,022,292 |
Goodnight |
February 8, 2000 |
Method of adjusting an engine load signal used by a transmission
controller
Abstract
A vehicle transmission controller responds of a load signal
representing a load on the vehicle engine. The load signal is
automatically and repeatedly adjusted as a function of an
operational status of the auxiliary vehicle function, and the load
signal is automatically adjusted during a shift of the
transmission.
Inventors: |
Goodnight; Trent Lynn
(Waterloo, IA) |
Assignee: |
Deere & Company (Moline,
IL)
|
Family
ID: |
22949118 |
Appl.
No.: |
09/250,780 |
Filed: |
February 12, 1999 |
Current U.S.
Class: |
477/121;
477/115 |
Current CPC
Class: |
F16H
59/14 (20130101); F16H 2059/503 (20130101); Y10T
477/688 (20150115); Y10T 477/693 (20150115) |
Current International
Class: |
F16H
59/14 (20060101); F16H 59/50 (20060101); F15H
059/34 () |
Field of
Search: |
;477/121,156,164,115,120
;74/11 ;701/50,53,54 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Marmor; Charles A.
Assistant Examiner: Parekh; Ankur
Claims
I claim:
1. In a vehicle having an engine, a transmission driven by the
engine and shiftable among a plurality of gears in response to
hydraulic pressure applied to shift control clutches, an auxiliary
function driven by the engine, a transmission controller for
controlling pressure applied to the shift control clutches as a
function of a load signal representing a load on the engine, a
method of adjusting the load signal to which the transmission
controller responds, comprising:
automatically and repeatedly determining a variable load factor
value as a function of an operational status of the auxiliary
function; and
adjusting the load signal used by the transmission controller as a
function of the variable load factor value;
controlling modification of the load factor value as a function of
previous modifications of the load factor value.
2. The method of claim 1, further comprising:
determining a speed ratio value representing a ratio of engine
speed to transmission output speed; and
modifying the load factor value as a function of the speed ratio
value.
3. The method of claim 2, further comprising:
increasing the load factor value if the speed ratio is not greater
than a certain value.
4. The method of claim 2, further comprising:
decreasing the load factor value if the speed ratio is not less
than a certain value.
5. The method of claim 2, further comprising:
preventing modification of the load factor value if the speed ratio
is within a range of values.
6. The method of claim 2, further comprising:
increasing the load factor value if the speed ratio is not greater
than a first value;
decreasing the load factor value if the speed ratio is not less
than a second value; and
preventing modification of the load factor value if the speed ratio
is between the first and second values.
7. The method of claim 1, wherein said vehicle further comprises an
operator controlled function switch for activating and deactivating
said auxiliary function, the method further comprising:
controlling modification of the load factor value as a function of
a status of the operator controlled function switch.
8. In a vehicle having an engine, a transmission driven by the
engine and shiftable among a plurality of gears, an auxiliary
function driven by the engine, a transmission controller for
controlling shifts as a function of a load signal representing a
load on the engine, a method of adjusting the load signal to which
the transmission controller responds, comprising:
determining a variable load factor value as a function of an
operational status of the auxiliary function;
determining a speed ratio value representing a ratio of engine
speed to transmission output speed;
modifying the load factor value as a function of the speed ratio
value; and
adjusting the load signal used by the transmission controller as a
function of the variable load factor value.
9. The method of claim 8, further comprising:
increasing the load factor value if the speed ratio is not greater
than a certain value.
10. The method of claim 8, further comprising:
decreasing the load factor value if the speed ratio is not less
than a certain value.
11. The method of claim 8, further comprising:
preventing modification of the load factor value if the speed ratio
is within a range of values.
12. The method of claim 8, further comprising:
increasing the load factor value if the speed ratio is not greater
than a first value;
decreasing the load factor value if the speed ratio is not less
than a second value; and
preventing modification of the load factor value if the speed ratio
is between the first and second values.
13. The method of claim 8, further comprising:
controlling modification of the load factor value as a function of
previous modifications of the load factor value.
14. The method of claim 8, wherein said vehicle further comprises
an operator controlled function switch for activating and
deactivating said auxiliary function, the method further
comprising:
controlling modification of the load factor value as a function of
a status of the operator controlled function switch.
Description
BACKGROUND OF THE INVENTION
The invention relates to a vehicle transmission shift control
system, and more particularly, to adaptive load-based powershift
transmission shift control system which responds to various
conditions, including the functional status of an auxiliary
function driven by the engine.
A known production tractor, such as a John Deere 8000 series
tractor, includes a powershift transmission (PST) controlled by a
plurality of solenoid operated transmission clutch control valves,
a power take off (PTO) controlled by a solenoid operated clutch.
These and other functional elements are controlled by
microprocessor-based vehicle control unit (VCU). Such a known
production tractor also includes a conventional hitch operated by a
solenoid operated hitch control valve and a plurality of solenoid
operated selective control valves (SCV). The hitch solenoid and the
SCV solenoid are controlled by a microprocessor-based hitch and SCV
control unit which communicates with the vehicle control unit (VCU)
by a conventional commercially available data bus. The commercially
available VCU executes a shift control program which controls the
shifting of the PST from one gear to another by controlling
pressure applied to the transmission control clutches as a function
of, among other things, the load as represented by the fuel flow or
load signal from an electronic engine control unit (ECU). To
achieve smooth shifts, generally, a higher clutch pressure is used
under high load conditions, and a lower clutch pressure is used
under lower load conditions.
However, when the engine is driving auxiliary functions, such as
the PTO or one or more SCVs, the load signal from the ECU will not
accurately represent the load which is actually applied to the
transmission. This can adversely effect the smoothness of certain
shifts. The production John Deere 8000 series tractor includes a
diagnostic mode feature wherein the operator can manually adjust
the load signal factor to compensate for the effects of operation
of an auxiliary function. However, with this diagnostic mode
feature, the compensation cannot be automatically or rapidly
modified to adjust for rapidly changing circumstances, nor can the
compensation be modified during an actual shift of the
transmission.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to provide a load
responsive powershift transmission control system wherein the load
factor is automatically adjusted in response to sensed
conditions.
A further object of the invention is to provide such a powershift
transmission control system wherein the load factor is
automatically adjusted during a shift of the transmission.
These and other objects are achieved by the present invention
wherein a vehicle transmission controller responds to a load signal
representing a load on the vehicle engine, and the load signal is
automatically and repeatedly adjusted as a function of an
operational status of the auxiliary vehicle function, and the load
signal is automatically adjusted during a shift of the
transmission.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic block diagram of a transmission control
system to which the present invention is applicable.
FIG. 2 is a logic flow diagram of an adaptive load factor
adjustment algorithm according to the present invention.
FIGS. 3-6 are is logic flow diagrams of subroutines which are part
of the adaptive load factor adjustment algorithm of FIG. 2.
DETAILED DESCRIPTION
Referring to FIG. 1, a vehicle power train includes an engine 10
(controlled by an electronic engine control unit 11, such as on the
production John Deere 8000 series tractors) which drives a power
shift transmission 12, which drives an output drive shaft 16 which
is connected to drive wheels (not shown). The power shift
transmission (PST) 12 includes a transmission 18 which is operated
by a set of pressure operated control elements or clutches 20 which
are controlled by a corresponding set of solenoid operated
proportional control valves 22. The transmission 18 may be a
powershift transmission such as available on the production John
Deere 8000 Series tractor, and as described in U.S. Pat. No.
5,011,465, issued Apr. 30, 1991 to Jeffries et al., and assigned to
the assignee of this application. The valves 22 may be two-stage
electrohydraulic valves, such as are also on the production John
Deere 8000 Series tractor, and as described in U.S. Pat. No.
4,741,364, issued May 3, 1988 to Stoss et al. and assigned to
applicant's assignee. The engine 10 also drives a conventional
power take off (PTO) drive 24 via PTO clutch 26, and drives a
hydraulic pump 28 which supplies pressurized hydraulic fluid to a
selective control valves (SCV) 30, all also as available on the
production John Deere 8000 Series tractor.
A vehicle control unit (VCU) 32, preferably one or more
microprocessor-based electronic control units, controls shifting of
the PST 12, and other functions, in response to signals supplied to
it by other components. A shift control lever unit 34, such as
described in U.S. Pat. No. 5,406,860, supplies a gear command
signal. A PTO switch unit 36, such as described in U.S. Pat. No.
5,380,964, supplies a PTO on/off signal. An SCV switch 38, such as
described in U.S. Pat. No. 5,343,775, supplies an SCV on/off
signal. Other function control devices (not shown) may be supplied
to control activation and deactivation of various other functions
which are driven or powered by the engine 10. The ECU 11 supplies a
fuel flow signal which represents the load on the engine. An engine
speed sensor 40, preferably a mag pick-up, supplies an engine speed
signal. An axle speed sensor 42, preferably a Hall effect sensor,
supplies an axle speed signal. Components 32-42 are preferably
similar to their counterparts found on the production John Deere
8000 series tractors, but similar commercially available components
could also suffice. Other load sensing devices (not shown), such as
torque sensors, may be supplied to provide a signal representative
of the load on the engine 10.
The known VCU 32, as used on the production John Deere 8000 series
tractors, controls shifting of the PST 12. To summarize, the
commercially available VCU executes a shift control program (not
shown) which controls the shifting of the PST from one gear to
another by controlling pressure applied to the transmission control
clutches 20 as a function of, among other things, the load as
represented by the fuel flow or load signal from the ECU 11 and a
load factor value. To achieve smooth shifts, generally, a higher
clutch pressure is used under high load conditions, and a lower
clutch pressure is used under lower load conditions. The load
factor value can be set by a dealer or an operator using a
diagnostic procedure built into the tachometer of the commercially
available John Deere 8000 series tractors.
Now, according to the present invention, the load factor is
automatically and repeatedly adjusted as a function of the
operational status of auxiliary engine driven functions, such as
the PTO and SCVs, is automatically and repeatedly adjusted during
the progress of a transmission gear shift, and as a function of
other conditions and parameters. For this purpose, the VCU 32
executes an adaptive load factor adjustment algorithm 100 shown in
FIG. 2.
The adaptive PTO/SCV load factor adjustment algorithm 100 is
entered at step 101. Step 102 determines if a particular shift of
the transmission 12 (which would benefit from this process) is in
progress, if the PTO/SCV load factor has not already been adjusted
by 20%, and if engine fuel flow (provided by ECU 11) is greater
than or equal to 12% of the rated fuel flow for the engine 10. If
any of these conditions are not met, step 102 ends the algorithm.
If all of these conditions are met, step 102 directs the algorithm
to step 104.
Step 104 operates as follows: If the PTO switch 36 is on and
adaptive PTO load compensation is enabled (such as by an operator
actuated switch or by the entering of a code), it directs control
to step 106; else if the SCV switch 38 is on and adaptive SCV load
compensation is enabled (such as by an operator actuated switch or
by the entering of a code), it directs control to step 108.
Otherwise, step 104 ends the algorithm.
Step 106 establishes PTO.sub.-- LOAD as a PTO load factor address
in a memory of the control unit 32 and directs the algorithm to
step 110. Step 108 establishes SCV.sub.-- LOAD as an SCV load
factor address in a memory of the control unit 32 and directs the
algorithm to step 110.
Step 110 sets a new load factor value, new.sub.-- load.sub.--
factor, to a previously stored value.
Step 112 operates as follows: A speed ratio value SR is determined
as the ratio of engine speed (from sensor 40) to transmission
output speed (from sensor 42). If SR is less than or equal to 121,
it directs control to subroutine 200; else if SR is less than or
equal to 130, it directs control to subroutine 300; else if SR is
greater than or equal to 175, it directs control to subroutine 400;
else if SR is greater than or equal to 170, it directs control to
subroutine 500. Otherwise, step 112 ends the algorithm. Subroutines
200-500 determine a new load factor value, as will be described
later in detail, and then return control to step 114 of the
adaptive PTO/SCV load factor adjustment algorithm 100.
Step 114 operates as follows: if the new load factor value
(returned by one of subroutines 200-500) is not equal to the
previously stored load factor value, the load factor value
"PTO/SCV.sub.-- Load.sub.-- Factor" is updated in step 116, else
the adaptive PTO/SCV load factor adjustment algorithm 100 is ended.
The updated load factor from step 116 is used by the commercially
available VCU 32 in the execution of the shift control program (not
shown). More specifically, the fuel flow load value (attributable
to the load from the vehicle axles) "Fuel.sub.-- Flow.sub.-- Axles"
is used to control transmission shifts, and is determined according
to the following relationship:
Fuel.sub.-- Flow.sub.-- Axles=Total.sub.-- Fuel.sub.--
Flow-((Total.sub.-- Fuel.sub.-- Flow-No.sub.-- Load.sub.--
Fuel.sub.-- Flow)*(PTO/SCV.sub.-- Load.sub.-- Factor/100)),
where "Total.sub.-- Fuel.sub.-- Flow" is the fuel flow value from
ECU 11, "No.sub.-- Load.sub.-- Fuel.sub.-- Flow" is constant
specific to a particular engine, and "PTO/SCV.sub.-- Load.sub.--
Factor" is the value determined by step 116.
For example, if Total.sub.-- Fuel.sub.-- Flow is 100% (tractor is
fully loaded), and No.sub.-- Load.sub.-- Fuel.sub.-- Flow is 20%,
and PTO/SCV.sub.-- Load.sub.-- Factor is 80%, then Fuel.sub.--
Flow.sub.-- Axles=100-((100-20)*80/100)=36%,
Turning now to FIG. 3, subroutine 200 is entered at step 202. Step
204 sets a flag to indicate that the PTO/SCV load factor has
previously been adjusted by 20% during this shift. Then step 206
operates as follows: If the PTO/SCV load factor has previously been
adjusted by 10% during this shift, then it directs control to step
208; else control is directed to step 210.
In step 208, if the new load factor value is less than 90%, control
is directed to step 212 which increases the new load factor value
by 10; else control is directed to step 214 which sets the new load
factor value equal to 100.
In step 210, if the new load factor value is less than 80, control
is directed to step 216 which increases the new load factor value
by 20; else control is directed to step 218 which sets the new load
factor value equal to 100. From steps 212, 214, 216 and 218 control
is directed to step 220 which returns control to step 114 of the
adaptive load factor algorithm 100.
Turning now to FIG. 4, subroutine 300 is entered at step 302. Step
304 operates as follows: If the PTO/SCV load factor has not
previously been adjusted by 10% during this shift, then it directs
control to step 306; else control is directed to step 314.
Step 306 sets a flag to indicate that the PTO/SCV load factor has
previously been adjusted by 10% during this shift.
Then, in step 308, if the new load factor value is less than 90,
control is directed to step 310 which increases the new load factor
value by 10; else control is directed to step 312 which sets the
new load factor value equal to 100.
From steps 310 and 312 control is directed to step 314. Step 314
returns control to step 114 of the adaptive load factor algorithm
100.
Turning now to FIG. 5, subroutine 400 is entered at step 402. Then
step 404 sets a flag to indicate that the PTO/SCV load factor has
previously been adjusted by 20% during this shift. Then step 406
operates as follows: If the PTO/SCV load factor has previously been
adjusted by 10% during this shift, then it directs control to step
408; else control is directed to step 410.
In step 408, if the new load factor value is greater than or equal
to 10, control is directed to step 412 which decreases the new load
factor value by 10; else control is directed to step 414 which sets
the new load factor value equal to 0.
In step 410, if the new load factor value is greater than 20,
control is directed to step 416 which decreases the new load factor
value by 20; else control is directed to step 418 which sets the
new load factor value equal to 0. From steps 412, 414, 416 and 418
control is directed to step 420 which returns control to step 114
of the adaptive load factor algorithm 100.
Turning now to FIG. 6, subroutine 500 is entered at step 502. Step
504 operates as follows: If the PTO/SCV load factor has not
previously been adjusted by 10% during this shift, then it directs
control to step 506; else control is directed to step 514.
Step 506 sets a flag to indicate that the PTO/SCV load factor has
previously been adjusted by 10% during this shift.
Then, in step 508, if the new load factor value is greater than 10,
control is directed to step 510 which decreases the new load factor
value by 10; else control is directed to step 512 which sets the
new load factor value equal to 0.
From steps 510 and 512 control is directed to step 514. Step 514
returns control to step 114 of the adaptive load factor algorithm
100.
The conversion of the above flow charts into a standard language
for implementing the algorithm described by the flow chart in a
digital computer or microprocessor, will be evident to one with
ordinary skill in the art.
A portion of the disclosure of this patent document contains
material which is subject to a claim of copyright protection. The
copyright owner has no objection to the facsimile reproduction by
anyone of the patent document or the patent disclosure, as it
appears in the Patent and Trademark Office patent file or records,
but otherwise reserves all other rights whatsoever.
While the present invention has been described in conjunction with
a specific embodiment, it is understood that many alternatives,
modifications and variations will be apparent to those skilled in
the art in light of the foregoing description. Accordingly, this
invention is intended to embrace all such alternatives,
modifications and variations which fall within the spirit and scope
of the appended claims.
* * * * *